The title makes the book instantly attractive to any geologist! I wrote a review for this book on Amazon a while ago. I gave it 3 stars. After reading reading another Darwin biography I would probably change it to 4 stars, just for the sheer volume of information. The book essentially catalogues Darwin's work prior to The Origin, which from a publication standpoint was almost entirely in the field of geology. She stresses notebook entries and letters suggesting that Darwin considered himself a geologist. But the author implicitly raises a couple of questions that I think are very interesting, and worthy of discussion. First, if Darwin had never written "The Origin" how would he be remembered by modern scientists and historians? Would he be remembered along with prominent 19th century English geologists like Sedgwick, Murchison, and Lyell. And second, was "The Origin" itself really a geological work? Could it be that in writing The Origin Darwin was addressing geologic problems such as the "species problem", extinctions in the fossil record, faunal succession, and in doing so he produced a work so revolutionary that its impact was not confined to the field of geology, impacting biology and all of natural science? If Darwin was a geologist, then he certainly had two careers, before The Origin and after. After The Origin/Descent/Sexual Selection trilogy his publications were almost exclusively in the field of Botany.
Brent